Microprocessor controlled demand defrost for a cooled enclosure

A refrigerated device including a cooled enclosure and an evaporator, the evaporator having refrigerant circulated therethrough, comprising:

• an air temperature sensor, the air temperature sensor being adapted to generate an air temperature signal indicative of air temperature within the enclosure;
• a refrigerant temperature sensor, the refrigerant temperature sensor being adapted to generate a refrigerant temperature signal indicative of refrigerant temperature;
• and
• a programmable controller, the programmable controller being adapted to compare the air temperature signal and the refrigerant temperature signal to calculate a difference between the air temperature and the refrigerant temperature, wherein the controller initiates a defrost routine for removing condensate from the evaporator if the difference between the air temperature and the refrigerant temperature is greater or equal to a defrost threshold, the defrost threshold being determined by a function of a minimum difference between the air temperature and the refrigerant temperature.